Residential generator systems

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lelectric

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I,ve seen some varried generator backup system installations for residential use. In one application their is a automatic transfer switch rated at 200 amps for a 200 amp panel. Backing up the 200 amp panel was a 10kw generator with a 50amp breaker on the generator. Is this a acceptable installation for a back up system or should the generator be sized to the panel!

Thanks lelectric
 
Re: Residential generator systems

It is an optional system, therefore there is no generator size requirement, only that it be sized for the required load. IMO if the generator feeder and OCPD are sized for the generator, you are OK.
 
Re: Residential generator systems

The generator would be sized for the connected load not the panel size if you wanted to carry the entire load. The generator is portected against overload by its breaker. There is no requirement to install a generator, you put in as large as a generator as you can afford.
 
Re: Residential generator systems

I would think that the generator connects to critical loads only, otherwise an overload would trip the breaker, and the stuff in the freezer would rot, and the homeowners might not be there to take care of it.
 
Re: Residential generator systems

rattus define a critical load in an article 702 optional standby system. It cannot be defined IMO, there is no life or public safety issues at hand to consider. There is no generator size requirements in 702 that I am aware of other than connected load. I like the way Tom put it, "buy what you can afford".

It will be the owners responsibility to turn off non desirable loads which may overload the generator.

[ December 13, 2004, 05:06 PM: Message edited by: dereckbc ]
 
Re: Residential generator systems

Doesn't matter. As long as he puts in some kind of transfer switch to protect the outside world, whatever size generator he installs is up to him. Its likely his actual load will be nowhere near the 200A size of the panelboard and its up to the HO to turn off the things he does not wnat on when the generator comes on. Or alternatively only power those circuits through the TS.
 
Re: Residential generator systems

Along these lines, when looking in NEC 2005 702.7, I find:
Code: 
702.7 Signals. Audible and visual signal devices shall be provided, where practicable, for the following purposes.
 (1) Derangement. To indicate derangement of the optional standby source.
 (2) Carrying Load. To indicate that the optional standby source is carrying load.
 
 Exception: Signals shall not be required for portable standby power sources.
I had this question for NEC 2002, but it seemed more restrictive and I gave up on the idea. NEC 2005 seems to have lightened up a little bit on this. My question: Can I install a 4-gang box full of three ways to serve as a BC TS for a generator? I saw a $210 BC TS that essentially did nothing more than this, but had a pilot light over each switch to show the generator was on for that circuit. The $210 option didn't meet my interpretation of the "Derangement" and "Carrying Load" requirements of 2002, in my opinion.

Now they have added this Exception, so now my three-way hootenany will be code acceptable, right? As long as I can drag my generator around?
 
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